Shutemup

84 944 Automatic

Now that my power steering is fixed, time for the next project.

When idling in drive, my rpm's will drop down to about 1000 then jump up to 1200. Sometimes after going back and forth a few times they will settle at 1200.

This only happens when I'l just rolling along in drive.

Never does it when I am setting still. Idles fine in park or when sitting at a stop light in drive.

Anyone have any ideas?

Shutemup

Could this be the same valve under the intake that was mentioned in another thread?

mikl1976

could be idle stabilizer

kennycoulter

what is that, and where?

kennycoulter

man it seems like when i post somewhere the topic dies. im real sorry about that. hope i never meet anyone in person.

art

Does an automatic have the same trailing throttle fuel shutoff as a 5 speed? If so maybe the throttle switch needs to be repositioned.

Another issue that has come up here is wear on the variable resistor in the AFM which causes wierdness in fuel delivery.

Do a thorough check for vacuum leaks, etc.

peanut

Hi Kenny
The air idle valve is a small canister just visible under the inlet manifold.
it has 2 hoses
Its job as I understand it is to stabilise the air delivery when de-accelerating. It is supposed to stop the engine cutting out when the revs drop sharply. If your engine is hunting (revs surge up and down continuously) when on tickover or the engine sometimes cuts out when you take your foot of the gas then this could be the culpret.
Check you have no air leaks anywhere on the hoses . The valves can be cleaned out but you have to take the inlet manifold off to get to it. If cleaning doesn't work you have to remove inlet mnfld again to fit new which is about $200 I believe.
There are lots of other things to check also which might be contributary

kennycoulter

oh ok. the auxiliary air valve. yeah i think my hoses are cracked. cause i can take other hoses and snap them so easily. my car surges less since its hotter out now. i think i paid around $50? from pelican parts american dollars. if this is what you are talking about.

peanut

wow they are $240 here in UK
glad to hear you're all fixed up now

Shutemup

I just went and replaced a few vaccum hoses for good luck. whenever I had them off it was doing the same thing.....rpm's dropping down and then jumping back up.

hmm

peanut

Is it ok now you have replaced the hoses?

Shutemup

I didn't drive it but I don't think so.

In my experiance with other vehicles, if you have a vaccum leak, your idle speed will go up, mine stayed the same after changing the hoses.

It really sound like that valve could be the culprit.

If I have to go to the trouble Of taking off the intake to get at it then I think I'll replace it.

Shutemup

anyone have any other ideas?

83na944

Sounds like the aux air valve. Seems I read that some people try squirting some PB Blaster in there and then blowing it out well. You can probably do that without removing the intake.

I don't think it would hurt anyway. Any other opinions about the Blaster squirt?

peanut

This valve seems to be featuring in a lot of threads lately. I have seen it called a lot of differant names so I suppose the manuals all differ in their discription but just so there is no misunderstanding ..I was referring to the cannister under the air inlet manifold with 2 hoses connected.

When I had my head gasket done last week the garage dropped the cannister in a bucket of petrol overnight and I don't know if that was the cause but my surging symptoms have certainly improved considerably Not quite gone away though.

If you are going to replace it , order the 2 shaped hoses and new jubilee clips as well cos you don't want to be getting that lot off again in a hurry!